Filadelfia

Disorders of the brain can exhibit considerable epidemiological comorbidity and often share symptoms, provoking debate about their etiologic overlap. We quantified the genetic sharing of 25 brain disorders from genome-wide association studies of 265,218 patients and 784,643 control participants and assessed their relationship to 17 phenotypes from 1,191,588 individuals. Psychiatric disorders share common variant risk, whereas neurological disorders appear more distinct from one another and from the psychiatric disorders. We also identified significant sharing between disorders and a number of brain phenotypes, including cognitive measures. Further, we conducted simulations to explore how statistical power, diagnostic misclassification, and phenotypic heterogeneity affect genetic correlations. These results highlight the importance of common genetic variation as a risk factor for brain disorders and the value of heritability-based methods in understanding their etiology.

BACKGROUND: The epilepsies are a clinically heterogeneous group of neurological disorders. Despite strong evidence for heritability, genome-wide association studies have had little success in identification of risk loci associated with epilepsy, probably because of relatively small sample sizes and insufficient power. We aimed to identify risk loci through meta-analyses of genome-wide association studies for all epilepsy and the two largest clinical subtypes (genetic generalised epilepsy and focal epilepsy). METHODS: We combined genome-wide association data from 12 cohorts of individuals with epilepsy and controls from population-based datasets. Controls were ethnically matched with cases. We phenotyped individuals with epilepsy into categories of genetic generalised epilepsy, focal epilepsy, or unclassified epilepsy. After standardised filtering for quality control and imputation to account for different genotyping platforms across sites, investigators at each site conducted a linear mixed-model association analysis for each dataset. Combining summary statistics, we conducted fixed-effects meta-analyses of all epilepsy, focal epilepsy, and genetic generalised epilepsy. We set the genome-wide significance threshold at p<1·66 × 10(-8). FINDINGS: We included 8696 cases and 26 157 controls in our analysis. Meta-analysis of the all-epilepsy cohort identified loci at 2q24.3 (p=8·71 × 10(-10)), implicating SCN1A, and at 4p15.1 (p=5·44 × 10(-9)), harbouring PCDH7, which encodes a protocadherin molecule not previously implicated in epilepsy. For the cohort of genetic generalised epilepsy, we noted a single signal at 2p16.1 (p=9·99 × 10(-9)), implicating VRK2 or FANCL. No single nucleotide polymorphism achieved genome-wide significance for focal epilepsy. INTERPRETATION: This meta-analysis describes a new locus not previously implicated in epilepsy and provides further evidence about the genetic architecture of these disorders, with the ultimate aim of assisting in disease classification and prognosis. The data suggest that specific loci can act pleiotropically raising risk for epilepsy broadly, or can have effects limited to a specific epilepsy subtype. Future genetic analyses might benefit from both lumping (ie, grouping of epilepsy types together) or splitting (ie, analysis of specific clinical subtypes). FUNDING: International League Against Epilepsy and multiple governmental and philanthropic agencies.

OBJECTIVE: SCN8A encodes the sodium channel voltage-gated α8-subunit (Nav1.6). SCN8A mutations have recently been associated with epilepsy and neurodevelopmental disorders. We aimed to delineate the phenotype associated with SCN8A mutations. METHODS: We used high-throughput sequence analysis of the SCN8A gene in 683 patients with a range of epileptic encephalopathies. In addition, we ascertained cases with SCN8A mutations from other centers. A detailed clinical history was obtained together with a review of EEG and imaging data. RESULTS: Seventeen patients with de novo heterozygous mutations of SCN8A were studied. Seizure onset occurred at a mean age of 5 months (range: 1 day to 18 months); in general, seizures were not triggered by fever. Fifteen of 17 patients had multiple seizure types including focal, tonic, clonic, myoclonic and absence seizures, and epileptic spasms; seizures were refractory to antiepileptic therapy. Development was normal in 12 patients and slowed after seizure onset, often with regression; 5 patients had delayed development from birth. All patients developed intellectual disability, ranging from mild to severe. Motor manifestations were prominent including hypotonia, dystonia, hyperreflexia, and ataxia. EEG findings comprised moderate to severe background slowing with focal or multifocal epileptiform discharges. CONCLUSION: SCN8A encephalopathy presents in infancy with multiple seizure types including focal seizures and spasms in some cases. Outcome is often poor and includes hypotonia and movement disorders. The majority of mutations arise de novo, although we observed a single case of somatic mosaicism in an unaffected parent.

BACKGROUND: encephalopathy and explored potential prospects of personalised medicine. METHODS: variants were collected from several diagnostic and research cohorts, as well as from 43 patients from the literature. Functional consequences and response to memantine treatment were investigated in vitro and eventually translated into patient care. RESULTS: Overall, de novo variants in 86 patients were classified as pathogenic/likely pathogenic. Patients presented with neurodevelopmental disorders and a spectrum of hypotonia, movement disorder, cortical visual impairment, cerebral volume loss and epilepsy. Six patients presented with a consistent malformation of cortical development (MCD) intermediate between tubulinopathies and polymicrogyria. Missense variants cluster in transmembrane segments and ligand-binding sites. Functional consequences of variants were diverse, revealing various potential gain-of-function and loss-of-function mechanisms and a retained sensitivity to the use-dependent blocker memantine. However, an objectifiable beneficial treatment response in the respective patients still remains to be demonstrated. CONCLUSIONS: encephalopathy is also frequently associated with movement disorder, cortical visual impairment and MCD revealing novel phenotypic consequences of channelopathies.

OBJECTIVE: Focal epilepsies are the most common form observed and have not generally been considered to be genetic in origin. Recently, we identified mutations in DEPDC5 as a cause of familial focal epilepsy. In this study, we investigated whether mutations in the mammalian target of rapamycin (mTOR) regulators, NPRL2 and NPRL3, also contribute to cases of focal epilepsy. METHODS: We used targeted capture and next-generation sequencing to analyze 404 unrelated probands with focal epilepsy. We performed exome sequencing on two families with multiple members affected with focal epilepsy and linkage analysis on one of these. RESULTS: In our cohort of 404 unrelated focal epilepsy patients, we identified five mutations in NPRL2 and five in NPRL3. Exome sequencing analysis of two families with focal epilepsy identified NPRL2 and NPRL3 as the top candidate-causative genes. Some patients had focal epilepsy associated with brain malformations. We also identified 18 new mutations in DEPDC5. INTERPRETATION: We have identified NPRL2 and NPRL3 as two new focal epilepsy genes that also play a role in the mTOR-signaling pathway. Our findings show that mutations in GATOR1 complex genes are the most significant cause of familial focal epilepsy identified to date, including cases with brain malformations. It is possible that deregulation of cellular growth control plays a more important role in epilepsy than is currently recognized.

OBJECTIVE: Benign familial infantile seizures (BFIS), paroxysmal kinesigenic dyskinesia (PKD), and their combination-known as infantile convulsions and paroxysmal choreoathetosis (ICCA)-are related autosomal dominant diseases. PRRT2 (proline-rich transmembrane protein 2 gene) has been identified as the major gene in all 3 conditions, found to be mutated in 80 to 90% of familial and 30 to 35% of sporadic cases. METHODS: We searched for the genetic defect in PRRT2-negative, unrelated families with BFIS or ICCA using whole exome or targeted gene panel sequencing, and performed a detailed cliniconeurophysiological workup. RESULTS: In 3 families with a total of 16 affected members, we identified the same, cosegregating heterozygous missense mutation (c.4447G>A; p.E1483K) in SCN8A, encoding a voltage-gated sodium channel. A founder effect was excluded by linkage analysis. All individuals except 1 had normal cognitive and motor milestones, neuroimaging, and interictal neurological status. Fifteen affected members presented with afebrile focal or generalized tonic-clonic seizures during the first to second year of life; 5 of them experienced single unprovoked seizures later on. One patient had seizures only at school age. All patients stayed otherwise seizure-free, most without medication. Interictal electroencephalogram (EEG) was normal in all cases but 2. Five of 16 patients developed additional brief paroxysmal episodes in puberty, either dystonic/dyskinetic or "shivering" attacks, triggered by stretching, motor initiation, or emotional stimuli. In 1 case, we recorded typical PKD spells by video-EEG-polygraphy, documenting a cortical involvement. INTERPRETATION: Our study establishes SCN8A as a novel gene in which a recurrent mutation causes BFIS/ICCA, expanding the clinical-genetic spectrum of combined epileptic and dyskinetic syndromes.

This summary corresponds to the translation into Spanish of the Special Communication published in the Journal of the American Medical Association in August 1996, along with the editorial published in the same issue "How to report Randomized Controlled Trials. The Consort Statement". It describes the Consolidated Standards for Preparation of Controlled Clinical Trials, prepared by a work group made up of members of the SORT Group and of the Asilomar Work Group, along with the director of a magazine and the author of the report on a clinical trial. The work was carried out by means of a Delphi process and the result was a check list and a process diagram. The check list is made up of 21 items that mainly refer to methods, results and discussions on the report of a controlled clinical trial, identifying the necessary information in order to be able to evaluate the internal and external value of the report, judging the improvement to be positive for the patient, the editors and the reviewers of the magazines.

OBJECTIVE: Pathogenic SLC6A1 variants were recently described in patients with myoclonic atonic epilepsy (MAE) and intellectual disability (ID). We set out to define the phenotypic spectrum in a larger cohort of SCL6A1-mutated patients. METHODS: We collected 24 SLC6A1 probands and 6 affected family members. Four previously published cases were included for further electroclinical description. In total, we reviewed the electroclinical data of 34 subjects. RESULTS: Cognitive development was impaired in 33/34 (97%) subjects; 28/34 had mild to moderate ID, with language impairment being the most common feature. Epilepsy was diagnosed in 31/34 cases with mean onset at 3.7 years. Cognitive assessment before epilepsy onset was available in 24/31 subjects and was normal in 25% (6/24), and consistent with mild ID in 46% (11/24) or moderate ID in 17% (4/24). Two patients had speech delay only, and 1 had severe ID. After epilepsy onset, cognition deteriorated in 46% (11/24) of cases. The most common seizure types were absence, myoclonic, and atonic seizures. Sixteen cases fulfilled the diagnostic criteria for MAE. Seven further patients had different forms of generalized epilepsy and 2 had focal epilepsy. Twenty of 31 patients became seizure-free, with valproic acid being the most effective drug. There was no clear-cut correlation between seizure control and cognitive outcome. Electroencephalography (EEG) findings were available in 27/31 patients showing irregular bursts of diffuse 2.5-3.5 Hz spikes/polyspikes-and-slow waves in 25/31. Two patients developed an EEG pattern resembling electrical status epilepticus during sleep. Ataxia was observed in 7/34 cases. We describe 7 truncating and 18 missense variants, including 4 recurrent variants (Gly232Val, Ala288Val, Val342Met, and Gly362Arg). SIGNIFICANCE: Most patients carrying pathogenic SLC6A1 variants have an MAE phenotype with language delay and mild/moderate ID before epilepsy onset. However, ID alone or associated with focal epilepsy can also be observed.

Cancer incidence among 8,004 patients hospitalized for epilepsy between 1933 and 1962 in the Filadelfia treatment community in Denmark was compared to that of the general population. Patients received powerful and prolonged treatment with phenobarbital, phenytoin, and other anticonvulsants. This new survey extends the follow-up from 1976 through 1984. Among 7,864 patients with epilepsy not known to have received radioactive Thorotrast, record linkage with national cancer incidence files identified 789 cancers, compared to 664 expected [relative risk (RR) = 1.19; 95% confidence interval = 1.11-1.27]. Significant risks were found for cancers of the brain and central nervous system (RR = 5.7; n = 118) and the lung (RR = 1.4; n = 106). The excess numbers of brain cancer were concentrated within 10 years of hospitalization (RR = 20.7; n = 80) and decreased significantly over time, which suggests that brain tumors account for the seizure disorder and are not due to phenobarbital exposure as suggested by some epidemiologic studies. No overall risk was apparent when brain cancers were excluded (RR = 1.03). Because bladder cancer was significantly decreased (RR = 0.6; n = 18), the excess risk of lung cancer may not have been related to the "anecdotal" heavy smoking reported among confined groups of epileptic patients in the early years of the study period. The incidence of malignant melanoma was also significantly low (RR = 0.5; n = 7), which suggested limited exposure to sunlight among confined patients. The risk of non-Hodgkin's lymphoma was increased, but not significantly (RR = 1.4; n = 16), which is interesting in view of previous reports suggesting an association with phenytoin. Overall, these data provide little evidence that phenobarbital and phenytoin are carcinogenic to humans, but the excess risks of lung cancer and non-Hodgkin's lymphoma among epileptic patients in our study deserve further evaluation.

Summary: Clinical effects at three different serum levels of sodium valproate (VPA) were compared in a triple‐blind, multiple crossover trial comprising 13 epileptic inpatients. Patients were selected regardless of seizure type, and all were in concomitant antiepileptic treatment, which was kept constant throughout the study. A significant relationship between the decrease in number of seizures and increasing VPA serum level was demonstrated. The relationship between VPA dose and serum level was curvilinear. Statistical evaluation of patients by seizure type in relation to clinical effect of VPA was only possible for secondary generalized seizures. Between phenytoin, phenobarbital, and carbamazepine and the different VPA serum levels no interactions could be demonstrated. Recorded side effects were always mild and transient. No obvious correlation between side effects and VPA serum level was established. RÉSUMÉ Les effets cliniques du valproate de soude, à trois différents taux sériques, ont été compares au cours d'essais en triple aveugle chez 13 malades hospitalisés. Ces malades ont ete choisis independamment du type de leurs crises et tous suivaient un traitement anti‐epileptique qui a ete maintenu constant pendant les essais. Une correlation significative a ete etablie entre la diminution du nombre de crises et l'augmentation du taux serique en valproate. La relation entre la dose de valproate et le taux serique etait curviligne. Une evaluation statistique des malades suivant le type de leur crise en relation avec les effets cliniques du valproate, a settlement ete possible pour les absences. Aucune interaction n'a été mise en evidence entre les taux seriques de phenobarbital, de phenytoine ou de carbamazepine et les differents taux seriques de valproate. Les effets secondaires ont toujours ete discrets et transitoires. Aucune correlation n'a été etablie entre les effets secondaires et le taux serique de valproate. RESUMEN En un estudio triple ciego con multiples crossover que incluyó 13 epilepticos hospitalizados se compara‐ron los resultados clt'nicos del valproato sódico (VPA) en tres niveles sericos diferentes. Los enfermos se seleccionaron sin tener en cuenta el tipo de ataque y todos estaban bajo un tratamiento antiepileptico concomitante que se mantuvo sin modificar a lo largo del estudio. Se demostrb una relacidn significativa entre la reducción del numero de ataques y el aumento de los niveles sericos del VPA. La relacidn entre la dosis de VPA y sus niveles sericos fue curvilinear. La valoracidn estadistica de los pacientes segiin el tipo de ataques y su relacidn con el efecto clinico del VPA solo pudo realizarse para las ausencias. No se pudo demostrar interaccidn alguna entre la feni‐toina, el fenobarbital y la carbamazepina y los diferentes niveles sericos del VPA. Los signos de intole‐rancia fueron siempre moderados y transitorios sin que se hayan podido establecer correlacidnes con los niveles de VPA en suero. ZUSAMMENFASSUNG Die klinische Wirkung dreier Serumspiegel des Natrium Valproat (VPA) wurde in einer Dreifachblind‐, mehrfachen crossover Studie an 13 stationär behan‐delten Anfallskranken untersucht. Die Patienten wur‐den ohne Riicksicht auf den Anfallstyp ausgesucht, alle erhielten eine antiepileptische Comedikation, die wahrend der Untersuchung konstant gehalten wurde. Es konnte eine signifikante Beziehung zwischen der Abnahme der Anfallshaufigkeit und steigendem VPA Serumspiegel nachgewiesen werden. Die Beziehungen zwischen der VPA‐Dosis und dem Serumspiegel waren curvilinear. Die statistische Bewertung der Beziehungen zwischen Anfallstyp und klinischer Wirkung des VPA war nur fur Absencen mdglich. Zwischen Phenytoin, Phenobarbital und Carbama‐zepin und verschiedenen VPA‐Serumspiegeln konnten keine Interaktionen festgestellt werden. Auftretende Nebenwirkungen waren immer milde und voriiberge‐hend. Es konnten keine Beziehungen zwischen Nebenwirkungen und VPA‐Serumspiegel hergestellt werden.

Standardized terminology for computer-based assessment and reporting of EEG has been previously developed in Europe. The International Federation of Clinical Neurophysiology established a taskforce in 2013 to develop this further, and to reach international consensus. This work resulted in the second, revised version of SCORE (Standardized Computer-based Organized Reporting of EEG), which is presented in this paper. The revised terminology was implemented in a software package (SCORE EEG), which was tested in clinical practice on 12,160 EEG recordings. Standardized terms implemented in SCORE are used to report the features of clinical relevance, extracted while assessing the EEGs. Selection of the terms is context sensitive: initial choices determine the subsequently presented sets of additional choices. This process automatically generates a report and feeds these features into a database. In the end, the diagnostic significance is scored, using a standardized list of terms. SCORE has specific modules for scoring seizures (including seizure semiology and ictal EEG patterns), neonatal recordings (including features specific for this age group), and for Critical Care EEG Terminology. SCORE is a useful clinical tool, with potential impact on clinical care, quality assurance, data-sharing, research and education.

In recent years, several genes have been causally associated with epilepsy. However, making a genetic diagnosis in a patient can still be difficult, since extensive phenotypic and genetic heterogeneity has been observed in many monogenic epilepsies. This study aimed to analyze the genetic basis of a wide spectrum of epilepsies with age of onset spanning from the neonatal period to adulthood. A gene panel targeting 46 epilepsy genes was used on a cohort of 216 patients consecutively referred for panel testing. The patients had a range of different epilepsies from benign neonatal seizures to epileptic encephalopathies (EEs). Potentially causative variants were evaluated by literature and database searches, submitted to bioinformatic prediction algorithms, and validated by Sanger sequencing. If possible, parents were included for segregation analysis. We identified a presumed disease-causing variant in 49 (23%) of the 216 patients. The variants were found in 19 different genes including &lt;i&gt;SCN1A, STXBP1, CDKL5, SCN2A, SCN8A, GABRA1, KCNA2, &lt;/i&gt;and &lt;i&gt;STX1B&lt;/i&gt;. Patients with neonatal-onset epilepsies had the highest rate of positive findings (57%). The overall yield for patients with EEs was 32%, compared to 17% among patients with generalized epilepsies and 16% in patients with focal or multifocal epilepsies. By the use of a gene panel consisting of 46 epilepsy genes, we were able to find a disease-causing genetic variation in 23% of the analyzed patients. The highest yield was found among patients with neonatal-onset epilepsies and EEs.

Disease-causing variants in STXBP1 are among the most common genetic causes of neurodevelopmental disorders. However, the phenotypic spectrum in STXBP1-related disorders is wide and clear correlations between variant type and clinical features have not been observed so far. Here, we harmonized clinical data across 534 individuals with STXBP1-related disorders and analysed 19 973 derived phenotypic terms, including phenotypes of 253 individuals previously unreported in the scientific literature. The overall phenotypic landscape in STXBP1-related disorders is characterized by neurodevelopmental abnormalities in 95% and seizures in 89% of individuals, including focal-onset seizures as the most common seizure type (47%). More than 88% of individuals with STXBP1-related disorders have seizure onset in the first year of life, including neonatal seizure onset in 47%. Individuals with protein-truncating variants and deletions in STXBP1 (n = 261) were almost twice as likely to present with West syndrome and were more phenotypically similar than expected by chance. Five genetic hotspots with recurrent variants were identified in more than 10 individuals, including p.Arg406Cys/His (n = 40), p.Arg292Cys/His/Leu/Pro (n = 30), p.Arg551Cys/Gly/His/Leu (n = 24), p.Pro139Leu (n = 12), and p.Arg190Trp (n = 11). None of the recurrent variants were significantly associated with distinct electroclinical syndromes, single phenotypic features, or showed overall clinical similarity, indicating that the baseline variability in STXBP1-related disorders is too high for discrete phenotypic subgroups to emerge. We then reconstructed the seizure history in 62 individuals with STXBP1-related disorders in detail, retrospectively assigning seizure type and seizure frequency monthly across 4433 time intervals, and retrieved 251 anti-seizure medication prescriptions from the electronic medical records. We demonstrate a dynamic pattern of seizure control and complex interplay with response to specific medications particularly in the first year of life when seizures in STXBP1-related disorders are the most prominent. Adrenocorticotropic hormone and phenobarbital were more likely to initially reduce seizure frequency in infantile spasms and focal seizures compared to other treatment options, while the ketogenic diet was most effective in maintaining seizure freedom. In summary, we demonstrate how the multidimensional spectrum of phenotypic features in STXBP1-related disorders can be assessed using a computational phenotype framework to facilitate the development of future precision-medicine approaches.

The identification of biomarkers of the transformation of normal to epileptic tissue would help to stratify patients at risk of epilepsy following brain injury, and inform new treatment strategies. MicroRNAs (miRNAs) are an attractive option in this direction. In this study, miRNA microarrays were performed on laser-microdissected hippocampal granule cell layer (GCL) and on plasma, at different time points in the development of pilocarpine-induced epilepsy in the rat: latency, first spontaneous seizure and chronic epileptic phase. Sixty-three miRNAs were differentially expressed in the GCL when considering all time points. Three main clusters were identified that separated the control and chronic phase groups from the latency group and from the first spontaneous seizure group. MiRNAs from rats in the chronic phase were compared to those obtained from the laser-microdissected GCL of epileptic patients, identifying several miRNAs (miR-21-5p, miR-23a-5p, miR-146a-5p and miR-181c-5p) that were up-regulated in both human and rat epileptic tissue. Analysis of plasma samples revealed different levels between control and pilocarpine-treated animals for 27 miRNAs. Two main clusters were identified that segregated controls from all other groups. Those miRNAs that are altered in plasma before the first spontaneous seizure, like miR-9a-3p, may be proposed as putative biomarkers of epileptogenesis.

We explored the current practice with respect to the neuropsychological assessment of surgical epilepsy patients in European epilepsy centers, with the aim of harmonizing and establishing common standards. Twenty-six epilepsy centers and members of "E-PILEPSY" (a European pilot network of reference centers in refractory epilepsy and epilepsy surgery), were asked to report the status of neuropsychological assessment in adults and children via two different surveys. There was a consensus among these centers regarding the role of neuropsychology in the presurgical workup. Strong agreement was found on indications (localization, epileptic dysfunctions, adverse drugs effects, and postoperative monitoring) and the domains to be evaluated (memory, attention, executive functions, language, visuospatial skills, intelligence, depression, anxiety, and quality of life). Although 186 different tests are in use throughout these European centers, a core group of tests reflecting a moderate level of agreement could be discerned. Variability exists with regard to indications, protocols, and paradigms for the assessment of hemispheric language dominance. For the tests in use, little published evidence of clinical validity in epilepsy was provided. Participants in the survey reported a need for improvement concerning the validity of the tests, tools for the assessment of everyday functioning and accelerated forgetting, national norms, and test co-normalization. Based on the present survey, we documented a consensus regarding the indications and principles of neuropsychological testing. Despite the variety of tests in use, the survey indicated that there may be a core set of tests chosen based on experience, as well as on published evidence. By combining these findings with the results of an ongoing systematic literature review, we aim for a battery that can be recommended for the use across epilepsy surgical centers in Europe.

Advances in gene discovery have identified genetic variants in the solute carrier family 6 member 1 gene as a monogenic cause of neurodevelopmental disorders, including epilepsy with myoclonic atonic seizures, autism spectrum disorder and intellectual disability. The solute carrier family 6 member 1 gene encodes for the GABA transporter protein type 1, which is responsible for the reuptake of the neurotransmitter GABA, the primary inhibitory neurotransmitter in the central nervous system, from the extracellular space. GABAergic inhibition is essential to counterbalance neuronal excitation, and when significantly disrupted, it negatively impacts brain development leading to developmental differences and seizures. Aggregation of patient variants and observed clinical manifestations expand understanding of the genotypic and phenotypic spectrum of this disorder. Here, we assess genetic and phenotypic features in 116 individuals with solute carrier family 6 member 1 variants, the vast majority of which are likely to lead to GABA transporter protein type 1 loss-of-function. The knowledge acquired will guide therapeutic decisions and the development of targeted therapies that selectively enhance transporter function and may improve symptoms. We analysed the longitudinal and cell type-specific expression of solute carrier family 6 member 1 in humans and localization of patient and control missense variants in a novel GABA transporter protein type 1 protein structure model. In this update, we discuss the progress made in understanding and treating solute carrier family 6 member 1-related disorders thus far, through the concerted efforts of clinicians, scientists and family support groups.

OBJECTIVE: Voltage-gated sodium channels (SCNs) share similar amino acid sequence, structure, and function. Genetic variants in the four human brain-expressed SCN genes SCN1A/2A/3A/8A have been associated with heterogeneous epilepsy phenotypes and neurodevelopmental disorders. To better understand the biology of seizure susceptibility in SCN-related epilepsies, our aim was to determine similarities and differences between sodium channel disorders, allowing us to develop a broader perspective on precision treatment than on an individual gene level alone. METHODS: We analyzed genotype-phenotype correlations in large SCN-patient cohorts and applied variant constraint analysis to identify severe sodium channel disease. We examined temporal patterns of human SCN expression and correlated functional data from in vitro studies with clinical phenotypes across different sodium channel disorders. RESULTS: Comparing 865 epilepsy patients (504 SCN1A, 140 SCN2A, 171 SCN8A, four SCN3A, 46 copy number variation [CNV] cases) and analysis of 114 functional studies allowed us to identify common patterns of presentation. All four epilepsy-associated SCN genes demonstrated significant constraint in both protein truncating and missense variation when compared to other SCN genes. We observed that age at seizure onset is related to SCN gene expression over time. Individuals with gain-of-function SCN2A/3A/8A missense variants or CNV duplications share similar characteristics, most frequently present with early onset epilepsy (<3 months), and demonstrate good response to sodium channel blockers (SCBs). Direct comparison of corresponding SCN variants across different SCN subtypes illustrates that the functional effects of variants in corresponding channel locations are similar; however, their clinical manifestation differs, depending on their role in different types of neurons in which they are expressed. SIGNIFICANCE: Variant function and location within one channel can serve as a surrogate for variant effects across related sodium channels. Taking a broader view on precision treatment suggests that in those patients with a suspected underlying genetic epilepsy presenting with neonatal or early onset seizures (<3 months), SCBs should be considered.

Summary The antiepileptic effect of valproate sodium (VPA) versus that of placebo has been evaluated in a controlled clinical trial (double‐blind, crossover type). The concentration of VPA and that of other antiepileptic drugs in serum, as well as findings by EEG, were recorded in the course of the trial. When VPA was added to the conventional antiepileptic treatment, which preferably was maintained constant, the frequency of seizures was significantly reduced in 21 patients (60%); it remained unchanged in 7 (20%), and increased in 7 (20%). No correlation between a reduced frequency of seizures and the concentration of VPA in serum was observed. Nor was there any significant correlation between the clinical and the EEG ratings of the therapeutic effect. The adverse reaction most commonly encountered was fatigue associated with hypersalivation. Alopecia developed in 2 patients. When VPA was administered together with phenobarbital, the dose of the latter had to be reduced by approximately 30% if the serum concentration of phenobarbital was to be maintained at a constant level. When patients were treated with phenytoin, additional d o s e s of VPA brought about a decrease in the serum concentration of phenytoin even though doses remained unchanged. RÉSUMÉ On a øvalué l'action antiépileptique du sodium valproate (VPA) par rapport a Paction d'un placébo dans une étude contrôlée (en double‐aveugle). On a pris en considération les taux de VPA et ceux des autres drogues antiépileptiques et les données EEG. Si on ajoute du VPA à un traitement antépileptique de préférence inchingé il y a une réduction des crises, significative chez 21 sujets (60%) pas de modification chez 7 (20%), et une augmentation des crises chez 7 (20%). Il n'y avait pas de corrélation entre la diminution des crises et les taux sériques de VPA et entre les effets cliniques et les donndée EEG. Les effets fré‐quemment observés étaient une fatigabilityé et une hypersalivation; une alopécie est survenue chez deux patients. Si on administrait du VPA avec du phénobarbital, la dose de ce dernier devait être réduite d'environ 30% pour le garder dans des taux sériques constants. Si les patients étaient en traitement avec de la diphénylhydantoine l'addition de VPA deaterminait une diminution des taux de DPH. RESUMEN En un ensayo chínico controlado (tipo doble ciego crossover) se han valorado los efectos antiepilépticos del valproato sódico (di‐ n ‐propilacetato sódico, VPA) compareándolos con placebo. En el transcurso del ensayo se anotaron las concentraciones en suero de VPA y otros antiepilépticos a la vez que los hallazgos del EEG. Si el VPA se añadia al tratamiento anticonvulsive convencional, que se mantuvo constante, se re‐dujo significativamente la frecuencia de los ataques en 21 enfermos (60%), no se modificó en 7 (20%) y au‐mentó en 7 (20%). No se observó ninguna correlación entre la reducción de la frecuencia de los ataques y la concentración del VPA en suero. No se observó ninguna correlación significativa entre la valoración clínica y electroencefalográfica de los efectos terapeúticos. La reacción adversa mas frecuente fué fatiga asociada a hipersalivación; dos enfermos desarrollaron alopecia. Cuando el VPA se administeró con fenobarbi‐tal se tuvo que reducir la dosis de este ultimo en un 30% si se intentaba mantener la concentración en suero del fenobarbital en un nivel constante. Si los enfermos también recibían difenilhidantoina, dosis adicionales de VPA producían una reducción en la concentración de difenilhidantoina, en suero, incluso manteniendo las mismas dosis administradas. ZUSAMMENFASSUNG Die antiepileptische Wirkung von Natriumvalproat (VPA) wurde gegenüber Placebo in einer kontrollier‐ten klinischen Untersuchung (gekreuzter Dop‐pelblindversuch) untersucht. Die Konzentrationen von VPA und anderen antiepileptischen Medikamenten wurdenim Serum bestimmt, die EEG‐Befunde regis‐triert. Fügte man VPS zur standardepileptischen Therapie hinzu, die bevorzugt konstant gehalten wurde, so reduziertesich die Anfallshäufigkeit bei 21 Patienten (60%), sie blieb unveranäert bei 7 (20%), erhöhte sich bei weiteren 7 Patienten (20%). Es wurde keinerlei Korrelation zwischen der verminderten Anfallshäufigkeit und der Serumkonzentration von VPA beobachtet. Ebenso fehlt eine signifikante Korrelation zwischen den klinischen Befunden und elektroen‐zephalographischen Ergebnissen und der Therapiewirkung. Die häufigste Nebenwirkung war Müdigkeit mit Hypersalivation; eine Alopezie wurde bei 2 Patienten beobachtet. Wenn VPA zusammen mit Phenobarbital verabfolgt wird, müßte die Dosis des letzteren um etwa 30% reduziert werden. Die Serumkonzentration von Phenobarbital konnte auf konstan‐tem Spiegel gehalten werden. Wenn Patienten mit DPH zusätzliche Dosen von VPA bekamen, verminderte sich die Serumkonzentration des DPH, obwohl die Dosierung unverändert blieb.

OBJECTIVE: Pathogenic variants in SCN8A have been associated with a wide spectrum of epilepsy phenotypes, ranging from benign familial infantile seizures (BFIS) to epileptic encephalopathies with variable severity. Furthermore, a few patients with intellectual disability (ID) or movement disorders without epilepsy have been reported. The vast majority of the published SCN8A patients suffer from severe developmental and epileptic encephalopathy (DEE). In this study, we aimed to provide further insight on the spectrum of milder SCN8A-related epilepsies. METHODS: A cohort of 1095 patients were screened using a next generation sequencing panel. Further patients were ascertained from a network of epilepsy genetics clinics. Patients with severe DEE and BFIS were excluded from the study. RESULTS: We found 36 probands who presented with an SCN8A-related epilepsy and normal intellect (33%) or mild (61%) to moderate ID (6%). All patients presented with epilepsy between age 1.5 months and 7 years (mean = 13.6 months), and 58% of these became seizure-free, two-thirds on monotherapy. Neurological disturbances included ataxia (28%) and hypotonia (19%) as the most prominent features. Interictal electroencephalogram was normal in 41%. Several recurrent variants were observed, including Ile763Val, Val891Met, Gly1475Arg, Gly1483Lys, Phe1588Leu, Arg1617Gln, Ala1650Val/Thr, Arg1872Gln, and Asn1877Ser. SIGNIFICANCE: With this study, we explore the electroclinical features of an intermediate SCN8A-related epilepsy with mild cognitive impairment, which is for the majority a treatable epilepsy.

BACKGROUND: Many genes are candidates for involvement in epileptic encephalopathy (EE) because one or a few possibly pathogenic variants have been found in patients, but insufficient genetic or functional evidence exists for a definite annotation. METHODS: To increase the number of validated EE genes, we sequenced 26 known and 351 candidate genes for EE in 360 patients. Variants in 25 genes known to be involved in EE or related phenotypes were followed up in 41 patients. We prioritized the candidate genes, and followed up 31 variants in this prioritized subset of candidate genes. RESULTS: Twenty-nine genotypes in known genes for EE (19) or related diseases (10), dominant as well as recessive or X-linked, were classified as likely pathogenic variants. Among those, likely pathogenic de novo variants were found in EE genes that act dominantly, including the recently identified genes EEF1A2, KCNB1 and the X-linked gene IQSEC2. A de novo frameshift variant in candidate gene HNRNPU was the only de novo variant found among the followed-up candidate genes, and the patient's phenotype was similar to a few recent publications. CONCLUSION: Mutations in genes described in OMIM as, for example, intellectual disability gene can lead to phenotypes that get classified as EE in the clinic. We confirmed existing literature reports that de novo loss-of-function HNRNPUmutations lead to severe developmental delay and febrile seizures in the first year of life.